Prosthetic knee

ABSTRACT

A prosthetic knee includes a housing and a brake member pivotally connected to the housing at a first location point. The brake member defines a first pair of slots along a posterior surface of the brake member. A knee shaft extends through the brake member and is secured within a cavity defined by the housing. The knee shaft defines a second plurality of slots along a posterior surface of the knee shaft corresponding in location to the first slots. An extension assist system includes an extension assist link with a body portion and a plurality of arm portions situated in the first slots defined in the brake member and in the second slots defined in the knee shaft. The arm portions are pivotally connected to the knee shaft at a second location point located within the second slots and a distance from the first location point.

TECHNICAL FIELD

The disclosure relates to a prosthetic knee for use with a prostheticsystem.

BACKGROUND

Artificial limbs, including leg prostheses, employ a wide range oftechnologies to provide solutions suitable to many differing needs. Fora trans-femoral amputee, basic needs in a leg prosthesis includestability, both while standing and during the stance phase of a walkinggait, and mechanical compatibility with the walking (or running) gait,and some manner of knee flexion during stance and swing phases of agait. Certain tradeoffs exist between security and stability and walkingor running performance (dynamic behavior).

A simple, non-articulable leg prosthesis (having no movable knee) mayprovide maximum stability but does not provide for an ideal gait. Also,sitting may be awkward if a person cannot bend his knee. Availablearticulating prosthetic knees provide improved walking or runningperformance but are lacking in stability and control. They are alsomechanically complex, expensive, or both. This can be especiallyproblematic for low activity users, such as elderly or fresh amputeesnot yet very skilled in controlling the knee.

The amount of control or stability required can vary from user to user,while known prosthetic knees have no adjustability.

There is a need for a prosthetic knee that provides stability in stanceand simulates more natural knee movement in swing.

SUMMARY

The disclosure describes various embodiments of a prosthetic kneeproviding a construction and design that facilitates stability in stancewhile also simulating more natural knee movement. The embodiments alsocan conveniently lock the knee in stance on demand.

The embodiments described can include a prosthetic knee that includes ahousing, a chassis, and a brake member pivotally connected to thehousing at a first location point and to the chassis at a secondlocation point. The brake member prevents rotation of the housingrelative to the chassis when the knee is loaded by a user instance,providing stability to the user. A knee shaft extends through the brakemember and is secured within a cavity defined by the housing.

An extension assist system includes a biasing mechanism arranged tocompress and push the knee back toward extension when the knee is inflexion, resulting in knee movement that is more natural and fluid. Thebiasing mechanism is located inside of the chassis and operativelyconnected to the knee shaft via an extension assist link.

The extension assist link includes a body portion operatively connectedto the biasing mechanism and a pair of arm portions in at least one slotdefined by the knee shaft. The arm portions are pivotally connected tothe knee shaft at a third location point located a distance from thefirst location point. By connecting the arm portions to the knee shaftwithin the at least one slot, the extension assist link canadvantageously distribute pressure and provide extra strength to theknee in supporting loads. The arm portions also provide additionalsupport in the knee to resist bending moments.

According to a variation, the lower surface of the extension assist linkdefines a convex portion that is complementary shaped to a concaverecess defined by the upper surface of a piston between the biasingmechanism and the extension assist link, providing consistent and smoothcontact between the piston and the extension assist link.

According to a variation, a lock piece is pivotally connected to thehousing and movable between a locked position in which the lock piece isengaged with a stop surface protruding from the brake member, and anunlocked position in which the lock piece is disengaged from the stopsurface. In the locked position, the engagement between the lock pieceand stop surface prevents rotation between the housing and the brakemember substantially preventing flexion of the knee. The large contactsurface area between the lock piece and stop surface reduces the lockpiece inadvertently slipping off of the stop surface. This allows theknee to be safely and securely locked such as during training,rehabilitation, and or other particularly demanding situations. The lockpiece can also be easily moved to the unlocked position, providingexcellent control to the user.

According to a variation, a brake-play adjustment fastener is on thechassis that engages the brake member. Friction components of the kneemay wear over time and develop brake play. If this occurs, the play at acontact point between the brake member and chassis should be adjusted.This can be adjusted using the brake-play adjustment fastener, whichrotates the entire brake member around the first location point.

According to a variation, a brake sensitivity screw and biasingmechanism are within a screw hole formed in the brake member. The loadrequired to activate the brake member can be advantageously regulated tothe individual user's weight and preferences by changing the brakemember preload using the brake sensitivity adjustment screw.

Additional features and advantages of embodiments of the presentdisclosure will be set forth in the description that follows, and inpart will be obvious from the description, or may be learned by thepractice of such exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood regarding the followingdescription, appended claims, and accompanying drawings.

FIG. 1 is schematic view showing a prosthetic system.

FIG. 2 is an isometric view of a prosthetic knee according to anembodiment.

FIG. 3 is an isometric view of the housing removed from the prostheticknee of FIG. 2 for ease of reference.

FIG. 4 is an isometric view of the shaft removed from the prostheticknee of FIG. 2 for ease of reference.

FIG. 5 is an isometric view of the brake clamp removed from theprosthetic knee of FIG. 2 for ease of reference.

FIG. 6 is a front view of the brake clamp in FIG. 5.

FIG. 7 is a cross-sectional view of the prosthetic knee of FIG. 2 infull extension according to an embodiment.

FIG. 8 is a cross-sectional view of the prosthetic knee of FIG. 2 inflexion according to an embodiment.

FIG. 9 is an isometric view of the extension assist link removed fromthe prosthetic knee of FIG. 2 for ease of reference.

FIG. 10 is a back view of the prosthetic knee of FIG. 2.

FIG. 11 is a detailed cross-sectional view of the prosthetic knee ofFIG. 2 showing the manual lock mechanism.

FIG. 12 is an isometric view of the manual lock mechanism removed fromthe prosthetic knee of FIG. 2 for ease of reference.

FIG. 13 is a side view of the prosthetic knee of FIG. 2.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

A better understanding of different embodiments of the invention may behad from the following description read with the accompanying drawingsin which like reference characters refer to like elements.

While the disclosure is susceptible to various modifications andalternative constructions, certain illustrative embodiments are in thedrawings and are described below. It should be understood, however,there is no intention to limit the disclosure to the embodimentsdisclosed, but on the contrary, the intention covers all modifications,alternative constructions, combinations, and equivalents falling withinthe spirit and scope of the disclosure.

For further ease of understanding the joint disclosed, a description ofa few terms is necessary. The term “upper” has its ordinary meaning andrefers to a location above, or higher than another location. Likewise,the term “lower” has its ordinary meaning and refers to a locationbelow, or underneath another location. The term “posterior” also has itsordinary meaning and refers to a location behind or to the rear ofanother location. The term “anterior” has its ordinary meaning andrefers to a location ahead or to the front of another location. Lastly,the terms “left” and right” have their ordinary meaning and as usedrefer to the left and right sides when viewing the prosthetic knee fromthe anterior side.

FIG. 1 schematically depicts a prosthetic system 1000 for a residuallimb 1001. The system 1000 includes a socket assembly 1003 that embracesa residual limb, a prosthetic knee 1007 connected to the socket assembly1003 by an adaptor 1011, a pylon 1013 connecting the knee 1007, and afoot 1015 connecting to the pylon 1013. The prosthetic knee 1007 can beany of the prosthetic knee disclosed embodiments.

In order to better understand the operation of the prosthetic kneedescribed, a basic discussion of the gait cycle is provided. A gaitcycle defines the movement of the leg between successive heel contactsof the same foot. The gait cycle has two phases: stance and swing. Thestance phase has three time periods: heel-strike, mid-stance andtoe-off. During mid-stance, the knee joint will be at full extension. Anactual knee joint will have flexion between heel-strike and mid-stanceand between mid-stance and toe-off. This is called “stance flexion.” Notall prosthetic joints provide for stance flexion, and for those that do,they are mechanically complex, expensive, or both. These prostheticjoints typically require frequent maintenance and replacement. Theamount of stance flexion required can vary from user to user, while mostprosthetic knees have no adjustability.

Maximum flexion of the knee joint, while walking, will occur at the endof the toe-off phase. Maximum flexion is typically determined in part bythe speed at which a person is walking. The faster a person walks thegreater maximum flexion, while the slower a person walks, the lessermaximum flexion. In a natural knee, maximum flexion can be controlledand limited via the musculature of the leg. In a prosthetic knee joint,some artificial means of controlling and limiting maximum flexion aretypically provided. Immediately following the end of the toe-off phasebegins the swing phase.

While the stance phase has three time periods, the swing phase has twotime periods: acceleration and deceleration. The acceleration phasebegins immediately following the maximum flexion during the toe-offphase. During the acceleration phase, the lower portion of the leg,comprising the shin and foot, swings back towards full extension. In anatural knee joint, a deceleration phase follows the acceleration phase,during which the lower portion of the leg continues to swing towardsfull extension. Some prosthetic joints do not provide for anydeceleration during the swing phase. Other prosthetic joints providedeceleration by using costly and bulky hydraulic or pneumatic cylinders.The deceleration required can vary from user to user, while mostprosthetic joints have no adjustability.

FIGS. 2-13 illustrate a first embodiment of a prosthetic knee 100 for aprosthetic system or assembly. The knee 100 includes a housing 102, achassis 104, and a load-dependent brake system 101 connecting thehousing 102 and the chassis 104. As seen in FIG. 2, a pyramid adaptor108 or a 4-prong adaptor can be positioned at a top of the housing 102and a distal tube clamp attachment 110, having a socket head cap screw112, for tightening can be positioned at the bottom of the chassis 104.

The load-dependent brake system 101 is arranged to selectively preventrotation of the housing 102 relative to the chassis 104 when the knee100 is loaded by a user in stance. When the load on the knee 100 isreleased, the load-dependent brake system 101 can be released so theknee 100 can swing or the housing 102 can rotate relative to the chassis104. This advantageously provides more natural and controlled movementof the knee. The load-dependent brake system 101 can include a brakemember 106, a knee shaft 122, and brake sleeve 160.

FIG. 3 shows the housing 102 removed from the knee 100 for ease ofreference. The housing 102 includes a main body 114 with first andsecond flanges 116, 118 that protrude from the main body 114 towards theposterior or back of the housing 102. The housing 102 defines a cavity103 in the bottom side thereof. The first flange 116 and the secondflange 118 can be parallel to each other and can each include a fastenerhole 120. The inner surface of each of the first and second flanges 116,118 can define a keyway 128. The keyway 128 can be a generallyrectangular slot or groove. The upper portion of the housing 102 definesa recess 211 and a pair of opposed retaining pin holes 125.

Referring now to FIG. 4, the knee shaft 122 of the load-dependent brakesystem 101 is insertable within the cavity 103 of the housing 102 so theknee shaft 122 is located inside of the cavity 103, extending betweenthe first and second flanges 116, 118. The knee shaft 122 is shown as acylindrical body but can be any suitable shape. A fastener hole 124 canbe defined in each end of the knee shaft 122.

The knee shaft 122 can be non-rotatably attached to the housing 102. Forinstance, the knee shaft 122 can be selectively retained within thecavity 103 of the housing 102 via at least one fastener 126 (shown inFIG. 2) respectively positioned in at least one fastener hole 120 of thehousing and at least one of the fastener holes 124 defined in the kneeshaft 122. A key 130 is defined on each end of the knee shaft 122.

When the knee shaft 122 is inserted into the cavity 103, the keys 130slide into the keyway 128 defined by the housing. This prevents relativerotation between the knee shaft 122 and the housing 102. It alsoprovides a solid connection between the knee shaft 122 and the housing102 by increasing the contact surface area between them. It furtheraligns the fastener holes 120 and the fastener hole 124, facilitatingassembly and/or disassembly of the knee 100.

The knee shaft 122 can define a through hole or pin hole 196 extendingbetween its opposing ends. The pin hole 196 can be generally paralleland eccentrically positioned relative to a first location point 150 orknee axis (shown in FIG. 8) described below. A posterior surface of theknee shaft 122 can also define at least one slot 198 that intersects thepin hole 196 between the opposing ends of the knee shaft 122. Theposterior surface of the knee shaft 122 is defined as being generallyopposed an anterior surface of the knee shaft 122 facing the secondlocation point 148.

As shown, the at least one slot can comprise a pair of slots 198. Inother embodiments, the at least one slot 198 can comprise a single slotsized and configured to receive arm portions of the extension assistlink described below. The pin hole 196 and the slots 198 are discussedin more detail below.

Referring now to FIGS. 5 and 6, the brake member 106 can be a brakeclamp movably connecting the housing 102 and the chassis 104 to oneanother. The brake clamp 106 can be pivotally connected to the housing102 and pivotally connected to the chassis 104, allowing the housing 102and the chassis 104 to be movably connected together.

The brake clamp 106 defines a main body 135 having an upper part 105 anda lower part 107 attached to the upper part 105. The upper part 105 canhave a width that is greater than a width of the lower part 107. Thebrake clamp 106 defines side portions 134, 136 protruding from the upperpart 105 towards the anterior of the brake clamp 106.

The side portions 134, 136 can be spaced apart and generally parallel toeach other. A pivot pin hole 138 can be defined in each of the sideportions 134, 136. A posterior surface of the brake clamp 106 defines apair of slots 201 that generally correspond to the slots 198 of the kneeshaft 122 when the knee shaft 122 is positioned within the cavity 103 ofthe housing 102. The posterior surface of the brake clamp 106 is definedas generally opposed an anterior surface of the brake clamp formed onthe terminal ends of the side portions 134, 146

A protruding step 207 can be defined on the brake clamp 106. The step207 can be between the slots 201 defined in the brake clamp 106. Thestep 207 can have any suitable configuration but is shown as asubstantially ramp-like protrusion forming a stop surface 137 and anupper curved surface. The stop surface 137 extends generallyperpendicular to the outer radial surface of the brake clamp 106. Thiscan create more normal contact between the step 207 and a lock piecedescribed below, reducing the lock piece inadvertently sliding off thestep 207. The upper curved surface of the step 207 helps the lock pieceto slide or move past the step 207 until the knee 100 reaches fullextension. In other embodiments, the step 207 can be a generallyrectangular member, a triangular member, or any other appropriatemember.

The step 207 can be attached to the brake clamp 106 or integrally formedon the brake clamp 106. The step 207 can have a width that is less thana width of the brake clamp 106. The width of the step 207 can generallycorrespond to a width of the recess 211 in the housing 102.

The brake clamp 106 also defines a shaft hole 132 extendingtherethrough. The shaft hole 132 can be generally parallel to the pivotpin holes 138. At least a portion of the brake clamp 106 is positionablewithin the cavity 103 of the housing 102, with the knee shaft 122extending through the shaft hole 132. The brake clamp 106 can alsodefine a slot 152 between the upper part 105, the lower part 107, and acontact pad 154 attached to a bottom side of the lower part 107.

The knee shaft 122 is rotatably received within the shaft hole 132 suchthat relative rotation between the housing 102 and the brake clamp 106is possible. For instance, the housing 102 and the knee shaft 122 arerotatable about the first location point 150 extending through the kneeshaft 122. Optionally, washers and/or bushings can be provided on theknee shaft 122 between the components of the knee 100 to help properlyalign, space, and/or fasten the individual components of the knee 100.

As seen in FIGS. 7 and 8, the chassis 104 defines a main body 156 and anupper portion 144 upwardly extending therefrom. The upper portion 144defines a pivot pin hole 146 passing therethrough. A pivot pin 140 canbe retained at each end by bearings 142 respectively positioned in thepivot pin holes 138 of the brake clamp 106. The pivot pin 140 passesthrough the pivot pin holes 138 and the pivot pin hole 146. The upperportion 144 of the chassis 104 is pivotally between the side portion 134and the side portion 136 of the brake clamp 106. The chassis 104includes a contact pad 158 attached to an upper side of the main body156.

The basicbrake function of the load-dependent brake system 101 will nowbe explained. When the knee 100 is loaded (e.g., foot on the ground) asshown in FIG. 7, the load-dependent brake system 101 moves to a brakedconfiguration or state in which a second location point 148 or actuationaxis allows relative rotation between the brake clamp 106 and thechassis 104, which loads a contact point between the contact pad 154 onthe brake clamp 106 and the contact pad 158 on the chassis 104. Thiscauses compression of the slot 152 defined by the brake clamp 106, whichcauses compression of the brake sleeve 160, which is fixedly attached tothe brake clamp 106.

The brake sleeve 160 is disposed within the shaft hole 132 and betweenthe brake clamp 106 and the knee shaft 122. Compression of the brakesleeve 160 on the knee shaft 122 creates friction against the knee shaft122, preventing rotation of the knee 100 about the first location point150. More particularly, compression of the brake sleeve 160 createsfriction that prevents rotation of the housing 102 about the firstlocation point 150. The brake sleeve 160 can be a C-shaped brake sleeveor any other appropriate brake sleeve. The brake sleeve 160 may beformed of metal such as copper, rubber, or any other material whichwould provide sufficient compression when the knee is loaded.

When the load is released from the knee 100, the load-dependent brakesystem 101 can move to a released configuration or state, in which theslot 152 and the brake sleeve 160 decompress, allowing the knee 100 toswing around the first location point 150 to the flexion position inFIG. 8.

A brake sensitivity adjustment system 109 can adjust the load requiredto activate the load-dependent brake system 101. The brake sensitivityadjustment system 109 includes a brake sensitivity adjustment screw 162and a biasing mechanism 164. The biasing mechanism 164 can be a springor any other suitable resilient member. The brake sensitivity adjustmentscrew 162 and the biasing mechanism 164 can be arranged within anadjustment screw hole 166 (FIG. 6) defined in the brake clamp 106. Thebiasing mechanism 164 can be within the adjustment screw hole 166between the lower part 107 and the brake sensitivity adjustment screw162. The biasing mechanism 164 engages the lower part 107 of the brakeclamp 106 and extends across the slot 152 to where it engages the brakesensitivity adjustment screw. The biasing mechanism 164 adjusts the loadrequired to compress the slot 152 when the brake sensitivity adjustmentscrew 162 is turned.

Turning the brake sensitivity adjustment screw 162 in a first direction(tightening), compresses the biasing mechanism 164, increasing thecompression preload of the brake clamp 106 or the force required toclose the slot 152 of the brake clamp 106. Turning the brake sensitivityadjustment screw 162 in a second direction (loosening), allows thebiasing mechanism 164 to decompress, decreasing the compression preloadof the brake clamp 106. By adjusting the compression preload of thebrake clamp 106, the load required to activate the knee brake can beregulated to the individual user's weight and/or preferences, providingmore natural and controlled movement of the knee 100.

A brake-play adjustment system 113 can adjust play that may develop inthe load-dependent brake system 101. The brake-play adjustment system113 can include a brake-play adjustment fastener or screw 168 and acontact pad 170. The brake-play adjustment screw 168 extends into a hole172 defined in the upper portion 144 of the chassis 104. The contact pad170 is secured within a recess defined on the anterior of the brakeclamp 106. The brake-play adjustment screw 168 is arranged to adjustablyengage the contact pad 170 on the brake clamp 106.

Different components of the load-dependent brake system 101 may wearover time and develop brake-play (e.g., an unwanted slight rotation inthe braked state). If this occurs, the play can be adjusted by using thebrake-play adjustment screw 168. For instance, turning the brake-playadjustment screw 168 in a first direction (tightening) advances thebrake-play adjustment screw 168 within the hole 172, engaging thecontact pad 170 on the brake clamp 106. This engagement creates a momentaround the second location point 148, which rotates the brake clamp 106relative to the chassis 104 about the second location point 148. Theposition of the brake clamp 106 relative to the chassis 104 can becontrolled and/or regulated, helping to maintain the contact pointbetween the contact pad 154 on the brake clamp 106 and the contact pad158 on the chassis 104, which limits play in the load-dependent brakesystem 101.

In swing phase, the knee 100 is returned to full extension via anextension assist system 115. A central component of the extension assistsystem 115 is a biasing mechanism or extension assist spring 178compressed when the knee 100 is flexed, and pushes the knee 100 back toextension. The extension assist spring 178 is located inside the chassis104 and operatively connected to the knee shaft 122 via a piston 174 andan extension assist link 182.

The piston 174 and extension assist spring 178 are retained within anextension assist housing including an inner housing 176 secured within acavity 180 defined in the main body 156 of the chassis 104. Theextension assist housing can also include an external housing 184provided coaxially with the inner housing 176 in the cavity 180. Theexternal housing 184 is arranged to receive the inner housing 176, thepiston 174, and a spring guide 186 and the extension assist spring 178.

In some embodiments, the external housing 184 can be adjustable. Forinstance, a clinician or user can rotate the external housing 184,moving it in an axial direction (e.g., upwards or downwards) to alterthe compression of the extension assist spring 178. This can vary thebiasing force applied to the piston 174 by the extension assist spring178, and the biasing force applied to an extension assist link 182 bythe piston 174. The level of biasing force generated by the extensionassist system 115 on the knee 100 toward extension can be adjusted asdesired or for example, to the user's walking speed.

Stored mechanical energy within the extension assist spring 178 whencompressed can be adjusted by rotating the external housing 184 via anopening 127 defined in the posterior or rear of the chassis 104. Thisadvantageously allows the extension assist system 115 to be adjustableand/or accessible to the user or clinician without having to disassemblethe knee 100. For instance, a clinician can adjust the compression ofthe extension assist spring 178 without having to remove a pylon fromthe distal tube clamp attachment 110 of the chassis 104.

The extension assist link 182 can exhibit any suitable configuration butis shown in FIG. 9 having a body portion 188 and first and second armportions 190, 192 protruding from the body portion 188. The body portion188 can connect the first and second arm portions 190, 192 to oneanother. The body portion 188 can include a cross member extendingbetween the arm portions 190, 192 and a base extending generallydownward from the cross member to a distal end or lower surface of theextension assist link 182.

The first and second arm portions 190, 192 are shown generally parallelto each other, each defining a pin hole 194. A lower surface of body 188of the extension assist link 182 can define a convex portion that iscomplementary shaped to a concave recess defined by the upper surface ofthe piston 174, providing consistent and smooth surface contact betweenthe piston 174 and the extension assist link 182.

As best seen in FIG. 10, the arm portions 190, 192 of the extensionassist link 182 can be within the slots 198 defined in the knee shaft122. The slots 198 can advantageously accommodate movement of the armportions 190, 192 relative the knee shaft 122 and help limit rotation ofthe knee shaft 122.

The extension assist link 182 can be pivotally connected to the kneeshaft 122 at a third location point 203 (best seen in FIG. 8) within theslots 198. The arm portions 190, 192 can be symmetric regarding thecentral plane of rotation. By connecting the arm portions 190, 192 tothe knee shaft 122 with the slots 198, the extension assist link 182 canadvantageously distribute pressure and provide extra strength to theknee 100 in supporting loads. The extension assist link 182 is alsoadvantageous since the arm portion 190 is connected to the arm portion192 by the body portion 188, providing additional support in the knee100 to resist a bending moment.

The third location point 203 is located a distance from the firstlocation point 150, about which the knee shaft 122 and the housing 102rotate. This creates an eccentric connection between the extensionassist link 182 and the knee shaft 122. Rotation of the knee shaft 122moves the extension assist link 182 in an upward direction or a downwarddirection. The third location point 203 can comprise a connection pinextending through the pin holes 194 in the extension assist link 182 andthe pin hole 196 in the knee shaft 122. The slots 201 defined in thebrake clamp 106 can accommodate movement of the arm portions 190, 192relative to the brake clamp 106.

In the swing phase or when the knee 100 is brought from the extensionposition (shown in FIG. 7) to the flexion position (shown in FIG. 8),the load-dependent brake system 101 is in the release state and thehousing 102 and knee shaft 122 can rotate about the first location point150. Because the extension assist link 183 is eccentrically connected tothe shaft, this rotation moves the extension assist link 183 and thepiston 174 in a downward direction, compressing the extension assistspring 178 within the cavity 182.

The stored mechanical energy in the extension assist spring 178 thenmoves the extension assist spring 178 back toward its equilibriumposition, which pushes the piston 174 in an upward direction. Thisforces the extension assist link 182 away from the spring guide 186,causing the knee shaft 122 and the housing 102 to rotate about the firstlocation point 150, which forces the knee 100 back toward the extensionposition.

Referring to FIGS. 11 and 12, the knee 100 can include a locking system117 allowing the knee 100 to be completely locked in one or moredifferent positions. The manual locking system 117 can include a lockpiece 205 and the step 207 defined on the brake clamp 106.

The lock piece 205 can have any shape but is shown having a generallywedge-like shape. The lock piece 205 has a body portion 119, first andsecond side arm portions 121 extending from the body portion 119, and agap 123 defined between the side arm portions 121. Each of the side armportions 121 can define a pin hole 209 extending therethrough.

The lock piece 205 can be within the recess 211 (FIG. 3) defined by thehousing 102 and pivotally connected to the housing 102 via a retainingpin 213 extending through the pin holes 209. Opposing ends of theretaining pin 213 can be within the retaining pin holes 125 in thehousing 102. The lock piece 205 can be fixedly attached to the retainingpin 213 so the lock piece 205 and the retaining pin 213 rotate together.Alternatively, the lock piece 205 can be rotatably attached to theretaining pin 213 so the lock piece 205 can rotate relative to theretaining pin 213. The retaining pin 213 can be integral to the lockpiece 205 or the retaining pin 213 can be separate from the lock piece205.

The lock piece 205 is rotatable between an unlocked position and alocked position. In the unlocked position, the lock piece 205 is rotatedaway from the brake clamp 106 so the lock piece 205 clears the step 207,allowing flexion or movement of the knee 100.

In the locked position, the lock piece 205 is rotated toward the brakeclamp 106 and engages the stop surface 137 of the step 207. Thisprevents flexion of the knee 100, advantageously limiting movement ofthe knee 100 during training, rehabilitation, and/or other particularlydemanding situations.

The posterior surface of the lock piece 205 may have a geometric shapewhich corresponds to the stop surface 137 defined by the step 207. Forinstance, the posterior surface of the lock piece 205 and the stopsurface 137 can both be planar or can form complementary angles. Inother embodiments, the stop surface 137 can include a slot or grooveconfigured to receive a key member defined on the lock piece 205. Inother embodiments, the stop surface 137 can include a concave portioncorresponding to a convex portion of the posterior surface of the lockpiece 205. The posterior surface of the lock piece 205 can be defined asbeing generally opposed the portion of the lock piece carrying theretaining pin 213.

The step 207 can be molded on the surface of the brake clamp 106, whichcan have a solid construction protruding from a profile of the brakeclamp 106 or the outer portion of the brake clamp 106 at the base of thestep 207. As seen, the lock piece 205 can also have a constructionarranged to resist deformation or failure, helping to provide solidcontact between the lock piece 205 and the stop surface 137. The size ofthe stop surface 137 and/or step 207 extending above the profile of thebrake clamp 106 also forms a larger contact surface area between thestop surface 137 and the lock piece 205, reducing the lock piece 205inadvertently slipping off of the step 207.

At least one the lock piece 205 or the step 207 can have a wider orthicker configuration, providing a greater locking strength. The stopsurface 137 and/or the lock piece 205 can be formed from metal, plastic,or another rigid material providing solid contact.

The lock piece 205 can be biased toward the locked position. Forinstance, a biasing mechanism or torsion spring 215 can be loaded on theretaining pin 213 and positioned between the side arm portions 121 ofthe lock piece 205. The torsion spring 215 can include a first arm 131insertable in a small hole formed in the brake clamp 106 and a secondarm 133 arranged to engage the housing 102. Stored mechanical energy inthe torsion spring 215 biases the lock piece 205 toward the lockedposition.

A release system 139 can allow a user or clinician to manually move thelocking system 117 to the unlocked position. For instance, when the lockpiece 205 is in the locked position, and hence the knee 100 in a lockedstate, sitting down can be difficult. The release system 139 can allow auser to release the lock piece 205 from the locked position to theunlocked position. As seen in FIG. 13, the release system 139 caninclude a lanyard, tether, or cable 217 attached to the lock piece 205that includes a handle portion. The cable can be threaded through thelock piece 205. A user can thread a distal end of the cable 217 througha fastener 225 having a tubular configuration, through the lock piece205, and back through the fastener 225. The user can then adjust thelength of the cable 217 as desired. With the length of the cable 217adjusted, the user then can secure (e.g., crimp) the fastener 225 on thecable 217, securely attaching the cable to the lock piece 205.

To manipulate the release system 139, the user can pull on the cablehandle to lift the lock piece 205 to the unlocked position. When theuser releases the cable, the lock piece 205 can return to the lockedposition when the knee 100 reaches full extension, allowing the lockpiece 205 to engage the stop surface 137 defined on the step 207.Optionally, the retaining pin 213 includes a head portion defining arecess arranged to receive a tool. The tool can manually rotate theretaining pin 213 which if fixedly attached to the lock piece 205 willrotate the lock piece 205.

The locking system 117 can include a locking feature arranged toselectively deactivate the lock piece 205. As seen in FIGS. 12 and 13, aset screw 219 can be disposed within a hole 141 (best seen in FIG. 3)defined in the housing 102. The set screw 219 is arranged to selectivelyengage a recess 145 defined in the lock piece 205.

To deactivate the locking function of the lock piece 205, a user canpull on the cable 217 or lift the lock piece 205 while tightening theset screw 219 such that it engages the recess 145 on the lock piece 205,preventing movement of the lock piece 205 into the locked position.

To activate the locking function of the lock piece 205, the user canunscrew the set screw 219 until it disengages from the recess 145.Optionally, the set screw 219 can be turned using a hex key 223 in FIG.14 or another appropriate type of tool.

Alternatively, the housing 102 can define a plurality of holes sorotation of the locking piece 205 can be locked in a number of differentpositions.

In other embodiments, the lock piece can have a generally triangularshape, a generally rectangular shape, or any other suitable shape. Inother embodiments, the extension assist link can have any suitableconfiguration such as a bar, a rod, an H-like member, or any otherappropriate linking structure. Further, while the extension assistmechanism is described including an extension assist spring, in otherembodiments, the extension assist mechanism can include a resilientlycompressible member/material, an elastic member, or any otherappropriate member. In addition, while the load-dependent brake systemis described including a brake clamp, in other embodiments, the brakeclamp 106 can be omitted. The knee can load-dependent brake systemcomprising a load-dependent ratchet mechanism connecting the housing andthe chassis, a friction based brake mechanism, a torsion spring typebrake mechanism, a locking cam-type brake mechanism, combinationsthereof, or any other suitable load-dependent brake system. The knee caninclude a single axis knee or the knee can include multiple knee axes.

While the load-dependent brake system is described including a brakeclamp, other types of braking mechanisms are possible. For instance, thebrake clamp can be omitted and the knee can include a load-dependentratchet mechanism connecting the housing and the chassis. In otherembodiments, the knee can include a friction based brake mechanism, atorsion spring type brake mechanism, combinations thereof, or othersuitable type of load-dependent brake system.

Further, the brake sensitivity adjustment system is described comprisinga brake adjustment screw and resilient member, however, it will beappreciated that other types of brake sensitivity adjustment systems arepossible. For instance, the brake sensitivity adjustment system caninclude one or more interchangeable resilient members or springsdisposed within the sensitivity adjustment screw hole between the lowerpart of the brake clamp and a plug member. The one or more springs canbe selected based on one or more properties (e.g., stiffness) to achievea desired compression preload of the brake clamp. While the brake-playadjustment system is described including a play adjustment screw andplay adjustment contact pad, in other embodiments, the brake-playadjustment system can include any suitable play adjustment mechanism.

In other embodiments, the lock mechanism can be formed at differentlocations on the knee so the knee can be locked in positions other thanfull extension. In other embodiments, the lock mechanism can include atorsion bar or any other suitable resilient member to bias the lockpiece.

While the foregoing embodiments have been described and shown,alternatives and modifications of these embodiments, such as thosesuggested by others may be made to fall within the scope of theinvention. While the hinge has been described in combination with a kneebrace, it will be understood that the principles described may beextended to other types of orthopedic and prosthetic devices.

1. A prosthetic knee comprising: a housing; a brake member pivotallyconnected to the housing at a first location point, the brake memberdefining a first plurality of slots along a posterior surface of thebrake member; a knee shaft extending through the brake member andsecured within a cavity defined by the housing, the knee shaft defininga second plurality of slots along a posterior surface of the knee shaftcorresponding in location to the first slots in the brake member; anextension assist system including an extension assist link having a bodyportion and a plurality of arm portions situated in the first slotsdefined in the brake member and in the second slots defined in the kneeshaft, the arm portions pivotally connected to the knee shaft at asecond location point located within the second slots and a distancefrom the first location point.
 2. The prosthetic device of claim 1,further comprising a piston secured between and engaging a biasingmechanism of the extension assist system and the extension assist link.3. The prosthetic device of claim 2, wherein a lower surface of theextension assist link defines a convex portion that is complementaryshaped to a concave recess defined by the upper surface of the pistonfor engagement therewith.
 4. The prosthetic knee of claim 2, furthercomprising: an extension assist housing receiving the piston and thebiasing mechanism, wherein the position of the extension assist housingis adjustable to adjust a biasing force exerted on the knee by thebiasing mechanism.
 5. The prosthetic knee of claim 1, further comprisinga chassis pivotally connected to the brake member.
 6. The prostheticknee of claim 5, further comprising: a pylon attached to the chassis;and an opening defined in a rear of the chassis, the opening arranged toprovide access for adjusting compression of the biasing mechanismwithout removal of a pylon from the prosthetic knee.
 7. The prostheticknee of claim 6, further comprising a brake sleeve interposed betweenthe brake member and the knee shaft.
 8. The prosthetic knee of claim 7,wherein when the knee is loaded by the user a contact point is loadedbetween the housing and the chassis to compress the brake member and thebrake sleeve about the knee shaft to create friction between the brakesleeve and the knee shaft to substantially prevent rotation of thehousing about the first location point.
 9. The prosthetic knee of claim1, further comprising a lock piece pivotally connected to the housingand movable between a locked position in which the lock piece is engagedwith a stop surface protruding from the brake member, and an unlockedposition in which the lock piece is disengaged from the stop surface.10. The prosthetic knee of claim 9, further comprising a torsion springbiasing the lock piece toward the locked position.
 11. The prostheticknee of claim 9, further comprising a set screw extending at least inpart through the housing, the set screw arranged to selectively preventthe lock piece from moving into the locking position.
 12. The prostheticknee of claim 11, wherein the set screw selectively engages the lockpiece by a recess defined in an outer surface of the lock piece.
 13. Theprosthetic knee of claim 9, further comprising a cable threaded throughthe lock piece and arranged for manually moving the lock piece to theunlocked position.
 14. The prosthetic knee of claim 1, wherein an innersurface of the housing defines at least one keyway comprising a slot orgroove having a rectangular cross-section arranged to receive at leastone corresponding key defined on the knee shaft.
 15. The prosthetic kneeof claim 1, further comprising a brake-play adjustment fastener engagingthe brake member, the brake-play adjustment fastener arranged toselectively rotate the brake member about a second location point.
 16. Aprosthetic knee comprising: a housing; a chassis; a brake memberpivotally connected to the housing at a first location point and to thechassis at a second location point, the brake member defining a firstpair of slots along a posterior surface of the brake member; a kneeshaft extending through the brake member and secured within a cavitydefined by the housing, the knee shaft defining a second pair of slotsalong a posterior surface of the knee shaft corresponding in location tothe first slots; an extension assist system including an extensionassist link having a body portion operatively connected to the biasingmechanism and a pair of arm portions situated in the first slots definedin the brake member and in the second slots defined in the knee shaft,the arm portions pivotally connected to the knee shaft at a thirdlocation point located within the second slots and a distance from thefirst location point.
 17. The prosthetic knee of claim 16, wherein theextension assist system comprises an extension assist spring arranged tocompress and push the knee back toward extension when the knee is inflexion.
 18. The prosthetic knee of claim 17, further comprising a brakesleeve interposed between the brake member and the knee shaft.
 19. Theprosthetic knee of claim 17, further comprising: a pylon attached to thechassis; and an opening defined in a rear of the chassis, the openingarranged to provide access for adjusting compression of the biasingmechanism without removal of a pylon from the prosthetic knee.
 20. Aprosthetic system comprising: a prosthetic socket arranged to receive aresidual limb; an adaptor connected to the prosthetic socket; and aprosthetic knee connected to the adaptor, the prosthetic knee including:a housing; a brake member pivotally connected to the housing at a firstlocation point, the brake member defining a first plurality of slotsalong a posterior surface of the brake member; a knee shaft extendingthrough the brake member and secured within a cavity defined by thehousing, the knee shaft defining a second plurality of slots along aposterior surface of the knee shaft corresponding in location to thefirst slots; an extension assist system including a biasing mechanismand an extension assist link having a body portion operatively connectedto the biasing mechanism and a plurality of arm portions situated in thefirst slots defined in the brake member and in the second slots definedin the knee shaft, the arm portions pivotally connected to the kneeshaft at a second location point located within the second slots and adistance from the first location point.